Microstructured effect pigments

ABSTRACT

The invention relates to flake-form effect pigments, characterised in that they consist of transparent or semitransparent materials and have a groove or grid structure, to processes for the production thereof, and to the use thereof.

The invention relates to flake-form effect pigments, characterised inthat the flakes are transparent or semitransparent and have a regulargroove or grid structure, to processes for the production thereof, andto the use thereof.

The achievement of angle-dependent optical effects in the coating oftwo-dimensional materials with thin layers has been known for some time.The prerequisite for this is a difference in the refractive indices ofthe thin layers compared with those of the surrounding media. Inphysical terms, partial reflection occurs on incidence of light at thephase boundaries. If the thicknesses of the layers are in the order ofmagnitude of the wavelength of light, the light components reflected atthe phase boundaries interfere, and extinction or reinforcement ofcertain wavelength regions occurs in white light. This results incoloured light, whose colour depends on the viewing angle. Suitabletwo-dimensional materials are films, foils, but also flakes, which maybe coated with the materials of different refractive index. An overviewof the principles of angle-dependent optical effects is given in G.Pfaff, P. Reynders, Chem. Rev., 1999, 99, 1963-1981.

Angle-dependent optical effects can alternatively also be produced viagrid structures, where the grid constant is preferably in the order ofmagnitude of from half the wavelength of light to three times thewavelength of light. The said grids can be the three-dimensional regulararrangement of spheres or cavities of equal size, a structural feature,as occurs, for example, in the opals known from nature. Such bodiesexhibit discrete to intense interference colours, provided that they aretransparent to light. U.S. Pat. No. 6,261,469 describes the productionof periodic structures of this type, with the structural feature beingregarded as similar to natural opals. The above-mentioned products arenot suitable for use in surface coatings and printing inks sincemultilayered grids are necessary for the occurrence of the interferencecolour and as a consequence particles of this type are too large forthese applications.

Analogous effects can also be achieved by films having a structuredsurface, with the grid structures again being regular and in the orderof magnitude of from half to three times the wavelength of light. Thefilms usually comprise a highly reflective metal layer, which isessential for the occurrence of strong interference colours. Thestructures are usually embossed, with the film either being embosseditself or a thermoplastic coating being embossed, if necessary afterwarming. The area of application of these films is principally indecorative applications, such as, for example, for gift foils.

U.S. Pat. No. 5,464,690 describes composite materials comprising a filmand a coating, where a diffraction pattern or holographic image isembossed on the coating. The coating and thus the optical element can betransferred to another substrate by heat sealing.

However, direct use of the films or the transfer of optical layers byheat sealing is only of limited applicability. The methods are notsuitable for relatively large or highly curved surfaces, nor for theproduction of paints and surface coatings.

JP63172779 claims a surface coating with interference colours whichcomprises interference pigments obtained by comminution of films havinga structured surface. The pigments consist of aluminium or ofaluminium-coated polymer film.

WO 9323481 describes structured metal pigments obtained by vapourdeposition coating of an embossed film with metal, detachment andcomminution of the vapour-deposited metal film. Layer packagescomprising metal layers and dielectric layers can also be applied byvapour deposition. Thus, multilayered pigments having a grid structurecan be obtained. The pigments exhibit strongly angle-dependent coloursand can be employed, for example, in surface coatings and in securityprinting.

The structured pigments described above consist either of metal flakesor comprise at least one metal layer and are thus opaque to light. Thelack of transparency of these pigments greatly restricts their potentialapplications in paints and surface coatings since there are virtually noopportunities for colour mixing, as is necessary for the surfacecoatings usually used. In order to achieve special colour effects, suchpigments have to be applied in multicoat finishes, which meansconsiderably increased work during coating and also during repair of anydamage. These pigments are also unsuitable for the production oftransparent articles, such as films, owing to their opacity to light.

There is therefore an urgent demand for pigments having anangle-dependent colour which can be formulated to a broad extent withother pigments and colorants and which exhibit the depth effect known ofconventional pearlescent pigments. In addition, the pigments should bethermally stable and chemically inert.

Surprisingly, it has been found that the microstructured effect pigmentsaccording to the invention achieve the complex requirement profilementioned above. The invention therefore relates to flake-form effectpigments, characterised in that the flakes are transparent orsemitransparent and have a regular groove or grid structure.

The effect pigments according to the invention exhibit the depth lustrewhich is typical of pearlescent pigments and at the same time exhibit adiscrete colour play when viewed at a flat angle. In addition, thepigments are thermally stable and chemically inert. Owing to thetransparency of the effect pigments according to the invention, they areparticularly suitable for use in blends with other pigments andfacilitate a wide variety of colour compositions with a series of colourshades at changing viewing angles. In contrast to the situation in thecase of structured pigments having metal layers from the prior art,which virtually only act in pale hues, the effect pigments according tothe invention are also suitable in dark hues. In addition, thecombination of colour effects as a consequence of the structure withinterference phenomena in the case of multilayered effect pigmentsenables novel colour effects to be achieved. Furthermore, the pigmentsaccording to the invention are suitable for use in transparentmaterials, such as, for example, films or plastic sheets.

The particular colour effects are caused by the groove or grid structureof the effect pigments according to the invention. The groove or gridstructure is located on the surface or in the body of the transparent orsemitransparent flakes and can consist of regularly arranged, parallelor crossed lines, hemispheres, spheres, pyramids, cubes orcorrespondingly shaped holes. The geometrical shape of the groove orgrid elements is of secondary importance for the colour effect; theimportant factor is the uniformity of the size of the groove or gridelements and their separations. In order to achieve particularly intensecolour effects, the separations of the groove or grid elements are inthe range 250-2000 nm and are thus in the order of magnitude of thewavelength of light.

The effect pigments according to the invention consist of transparent orsemitransparent flakes, where the transparency of the pigments accordingto the invention is >20%, preferably >50%, based on the individualparticle and on white light from a quartz lamp. Methods for thedetermination of the transparency of small flakes are known, andinstruments for this purpose are commercially available. For example, amicrospectrometer from the SEE 1000 series from SEE Inc, Middleborough,Mass.; USA, is suitable. Suitable materials for the transparent orsemitransparent flakes are, for example, magnesium fluoride, metaloxides, metal suboxides, nitrides, oxynitrides or phosphates. Thepigments according to the invention preferably consist of one or morelayers of the transparent or semitransparent materials.

The transparent or semitransparent materials are preferably metaloxides, such as, for example, silicon oxide, aluminium oxide, ironoxide, zirconium oxide, tantalum oxide or titanium oxide. The effectpigments according to the invention preferably comprise at least onetransparent or semitransparent material having a refractive indexof >1.7. In particular, the oxides of the elements aluminium, titanium,iron, zirconium or mixtures of these materials are employed for thispurpose.

In the simplest embodiment, the effect pigments according to theinvention consist only of one layer of a transparent or semitransparentmaterial and have the groove or grid structure on one of the twosurfaces. These are preferably layers of metal oxides having arefractive index of >1.7, such as, for example, aluminium oxide,titanium oxide, iron oxide, zirconium oxide or mixtures of these oxides.

The thickness of the pigment flakes can vary in broad ranges and is notcrucial for the colour effects occurring. The thickness is preferably0.3 to 2 μm. The diameter of the pigments according to the invention canbe varied in broad ranges, depending on the application. Preferred sizesare in the range from 5 to 500 μm and in particular between 10 and 100μm.

Alternative effect pigments which are likewise in accordance with theinvention comprise a transparent or semitransparent support materialwhich has a groove or grid structure on one of the surfaces and isprovided with further layers of a transparent or semitransparentmaterial. Suitable support materials are all transparent orsemitransparent materials known to the person skilled in the art, suchas, for example, magnesium fluoride, metal oxides, nitrides,oxynitrides, phosphates, but in particular metal oxides, such as, forexample, silicon dioxide, titanium dioxide, titanium suboxides,zirconium dioxide, iron(III) oxide, iron titanates or chromium oxide.

The coating can consist of all transparent or semitransparent materialsknown to the person skilled in the art, such as, for example, metals ormetal oxides. Suitable metals are, for example, chromium, aluminium,nickel, silver, gold, titanium or copper. In order to guarantee thesemitransparency of the metal layers, the thickness of the metal layers,depending on the metal, is 3 to 20 nm, preferably 5 to 10 nm. Thecoating preferably consists of metal oxides and in particular of metaloxides having a refractive index of >1.7, such as, for example,aluminium oxide, titanium oxide, iron oxide, zirconium oxide or mixturesof these oxides. The coating of the support material with at least onefurther layer enables the colour effects of the pigments according tothe invention to be varied through interference phenomena. The thicknessof the metal-oxide coating on the support material is 10 to 300 nm,preferably 20 to 150 nm. Through control of the thickness of the coatingin a manner familiar to the person skilled in the art, the coloureffects achieved by the pigments according to the invention can beinfluenced further.

In a further embodiment, the pigments according to the invention areformed by the regular arrangement of monodisperse spheres of transparentor semitransparent materials embedded in a matrix. In the simplestembodiment, the monodisperse spheres consist, for example, of polymersor a metal oxide, preferably having a refractive index >1.7, such as,for example, aluminium oxide, titanium oxide or zirconium oxide.Alternatively, the monodisperse spheres may also consist of othertransparent or semitransparent materials and be provided with furtherlayers. The sphere bodies are preferably of metal oxides and inparticular of silicon oxide. These spheres may be coated with othertransparent or semitransparent materials, preferably with a metal oxidehaving a refractive index >1.7. Particularly suitable for this purposeare titanium oxide, aluminium oxide, iron oxide, zirconium oxide ormixtures of these materials. However, the spheres may also comprisesemitransparent or opaque metal layers, provided that the transparencyof the flakes comprising such spheres is greater than 20%.

The structure of the monodisperse spheres and processes for theproduction thereof are described, for example, in EP 0 803 550. Thediameter of the spheres can be 100 to 1000 nm, preferably 200 to 700 nm.In order to fix the coated or uncoated spheres, they are embedded in amatrix in the case of the pigments according to the invention. Thematerial for the matrix can be organic binders, but also inorganicmaterials. Suitable organic binders are all film-forming organicpolymers known to the person skilled in the art which can be crosslinkedafter formation of the film and formation of the regular grid structure.Suitable matrix materials are, for example, epoxy resins,melamine-formaldehyde resins or acrylates. Suitable inorganic matrixmaterials are, in particular, network-forming materials, such as, forexample, metal titanates, metal aluminates, oxides, such as titaniumoxide, aluminium oxide, zirconium oxide or silicon oxide. Preference isgiven to the use of silicon dioxide.

A process for the production of structured metal-based pigments which ismentioned in the prior art is substantially based on the embossing ofstructures in existing metal foils. This process is not suitable for theproduction of the effect pigments according to the invention. Anotherknown process is based on the coating of a structured foil by vacuumvapour deposition. This process is very complex, the vapour depositioncoating with low-volatility metal oxides requires high energyexpenditure and long residence times.

The invention therefore also relates to processes for the production ofthe effect pigments according to the invention, characterised in that abody provided with a groove or grid structure is coated with atransparent or semitransparent material, and the flake-form effectpigment is obtained either by detachment from the structured body or byseparation from a support together with the structured body. In afurther embodiment, the effect pigments according to the inventionproduced by this process may additionally be coated with further layersof a transparent or semitransparent material, for example with metaloxides or metals, such as, for example, chromium, aluminium, nickel,silver, gold, titanium or copper. The coating is preferably carried outwith metal oxides and in particular with silicon dioxide, aluminiumoxide, titanium oxide, iron oxide, zirconium oxide or mixtures of theseoxides. In this way, pigments which exhibit particularly intense colourscan be produced.

The bodies provided with a grid structure can be, for example, in theform of a correspondingly structured film, a structured tape or a drumhaving a structured surface. Other structured materials known to theperson skilled in the art can likewise be employed. The grid structureon the bodies can consist of regularly arranged, parallel or crossedgrooves, lines, hemispheres, spheres, pyramids, cubes or correspondinglyshaped holes. Preference is given to the use of grids comprisingregularly arranged grooves or spheres.

Grids comprising regularly arranged spheres can be produced, forexample, by application of a suspension of monodisperse spheres and afilm-forming matrix to a support having a smooth surface, such as, forexample, a film. EP 0 216 278 discloses monodisperse spheres of thistype. After application of the film, the particles are further arrangedin closest spherical packing by the surface forces and the materialtransport during the drying operation. The interspaces between thespheres themselves and the interspaces between the spheres and thesurface of the support are filled by the matrix material. Suitablematrix materials are the transparent or semitransparent materialsmentioned in this application, but also organic binders. The formationof nanostructures of this type by self-organisation of particles and themechanisms for this are described, for example, by F. Burmeister, J.Boneberg, P. Leiderer, Physikalische Blätter 2000, 56, 49-50. Theparticles arranged in this way can be fixed in the matrix bycrosslinking of the film-forming matrix material. The crosslinking herecan take place in all manners known to the person skilled in the art,such as, for example, condensation or addition reactions, polymerisationof suitable monomers and by thermally, photochemically or pH-inducedcrosslinking. The film obtained can be dried, washed and detached fromthe support. In this way, bodies structured with spheres are obtainedwhich can be employed in the process for the production of the pigmentsaccording to the invention. In addition, this procedure is also suitablefor the direct production of the particular embodiment of the pigmentsaccording to the invention in which a combination of a regular grid ofcoated spheres with a transparent or semitransparent material ispresent. The pigments according to the invention can be obtained bydetachment of the film from the spheres embedded in the binder andcomminuting the film. The sphere grid is accordingly located in the bodyof the pigments according to the invention. Preference is given to theuse of spheres made from materials of high refractive index (>1.7) orspheres coated with high-refractive-index materials.

The coating of the structured bodies for the production of the pigmentsaccording to the invention can be carried out wet-chemically, by thesol-gel process or via PVD or CVD processes. The structured body herecan be applied to a support, such as, for example, an embossed releaselayer on a film or a drum.

In the case of coating by the sol-gel process, metal alkoxides arepreferably applied to the structured bodies in the form of a solution,the metal alkoxides are decomposed hydrolytically using water, theresultant film is dried and either detached from the structured body ordetached from a support in combination with the structured body. Furtherembodiments can be derived by the person skilled in the art in anobvious manner.

Alternatively, the coating can also be carried out wet-chemically, forexample by application of aqueous sols and solutions to the structuredbodies, precipitation of a layer, drying and detachment of the coatingfrom the body or from a support together with the body. A preferredexample is the deposition of silicon dioxide from water-glass. Inaddition, all processes known to the person skilled in the art for theprecipitation and formation of the layer-forming materials are suitable.

The coating of a structured body for the production of the effectpigments according to the invention can also be carried out via PVD orCVD processes. These processes are known from the literature, forexample from U.S. Pat. No. 3,123,489.

In the coating, the body structure is in the simplest case transferredto the coating material. The structured body acts in the coating asnegative for the surface of the pigment particles that was in contactwith the body. The opposite surface which was not in contact with thebody generally exhibits only a weak image of the relief and may becompletely flat in the case of thicker particles. The pigments accordingto the invention formed in this way can be detached from the structuredsupport material and comminuted. Alternatively, pigments according tothe invention can be obtained if the transparent or semitransparentmaterial applied is separated off in combination with the structuredbody. This procedure is particularly suitable for the production of thepigments according to the invention in which a regular grid of mono- ormulticoated spheres is present.

In a further embodiment, the resultant pigments according to theinvention can be coated further, for example with metal oxides ormetals, optionally mixed with colorants. Suitable metals here are, forexample, chromium, aluminium, nickel, silver, gold, titanium or copper.Suitable for the deposition of the metals by CVD or PVD processes areall precursors and process variants known to the person skilled in theart. In addition, the transparent or semitransparent materials of thepigments according to the invention may likewise, in their respectiveembodiment, comprise colorants for further colouring of the pigments.

Further processes for the production of the effect pigments according tothe invention can be used in a manner familiar to the person skilled inthe art.

Owing to their advantageous properties, the effect pigments according tothe invention are suitable for a broad range of applications. Theinvention therefore also relates to the use of the effect pigmentsaccording to the invention in cosmetics, surface coatings, paints,plastics, films, in security printing, as security feature in documentsand identity cards, for laser marking, for colouring seed, for colouringfoods or in medicament coatings.

In the case of cosmetics, the pigments according to the invention areparticularly suitable for products in decorative cosmetics, such as, forexample, nail varnishes, colouring powders, lipsticks or eyeshadows. Onuse of the pigments in paints and surface coatings, all areas ofapplication known to the person skilled in the art are possible, suchas, for example, powder coatings, automobile paints, printing inks forgravure, offset, screen or flexographic printing and for surfacecoatings in outdoor applications. In addition, the pigments according tothe invention can be used for pigmenting films and plastics, for examplefor agricultural sheeting, infrared-reflective films and panes, giftfoils, plastic containers and mouldings for all applications known tothe person skilled in the art. Owing to the particular angle-dependentcolour effects, the pigments according to the invention are alsosuitable for use in security printing and in security-relevant featuresfor, for example, forgery-proof cards and identity papers, such as, forexample, entry tickets, personal identity cards, banknotes, cheques andcheque cards, and for other forgery-proof documents. In the area ofagriculture, the pigments can be used for colouring seed and otherstarting materials, in addition in the foods sector for pigmentingfoods. The pigments according to the invention can likewise be employedfor pigmenting coatings in medicaments, such as, for example, tablets ordragées.

Owing to the transparency, the effect pigments according to theinvention are suitable for the pigmentation of transparent films whichretain their transparency and in particular for use in blends are mixedwith all known organic and/or inorganic colorants, such as, for example,organic dyes, organic pigments, inorganic single- or multilayeredpigments, inorganic dyes or pigments. It is thus possible to achieve ina simple manner novel colour effects which can only be achieved withdifficulty using the conventional structured metal-based pigments.

A particular potential application of the effect pigments according tothe invention consists in their use as tracers in mixtures with furtherorganic and/or inorganic colorants. Tracers are frequently employed inmodern products as identification agents. With their aid, theauthenticity of a product can be established or the origin of a productreconstructed. Common tracers are based on fluorescent, radioactive orluminescent substances which are added to the product to be protected inthe form of a powder, suspension or liquid. These substances arefrequently toxicologically and environmentally unacceptable or requirespecial apparatuses and instruments for their detectability.

The effect pigments according to the invention can be added to thecolorants to be marked or products produced therefrom, such as, forexample, surface coatings, powders, inks or suspensions, using allmethods known to the person skilled in the art. The proportion of thetracer in the product to be marked is usually ≦5% by weight, based onthe marked product, and preferably <2% by weight and very particularlypreferably 0.1-1% by weight.

Depending on the size of the effect pigments according to the invention,the tracer in the mixtures can be detected very simply by means of amicroscope or by means of the scanning electron microscope. Chemicallyand toxicologically, these tracers behave like other effect pigments andare thus chemically inert and toxicologically acceptable. The effectpigments according to the invention can be admixed in very small dosage,so that the colouristic properties in the application are thus notsignificantly influenced. Since the effect pigments according to theinvention specifically adapted to the customer wishes for thisapplication are not commercially available, adequate copy protection ofthe mixture to be marked is ensured.

Owing to the stability and chemically inert character, the effectpigments according to the invention can be employed simply and withoutproblems and converted into formulations. This invention likewiserelates to formulations comprising the effect pigments according to theinvention.

The following examples are intended to explain the invention in greaterdetail, but without limiting it.

EXAMPLES Example 1

A polyethylene terephthalate film with a thickness of 100 μm whosesurface is embossed with a regular groove structure having a grooveseparation of 1 μm is coated by the dip-casting method with a sodiumwater-glass solution (23% by weight of sodium orthosilicate) comprising0.1% by weight of a commercially available wetting agent (for exampleTriton® X-100) as wetting aid and flow-control agent. The sodiumwater-glass film is dried using air at 50° C. The dry film with athickness of about 600 nm is detached from the substrate in the form ofcoarse flakes and subsequently washed at pH 5, during which the pH ofthe bath is kept constant using dilute hydrochloric acid. After thewashing, the SiO₂ flakes are dried, then calcined at 700° C. andsubsequently crushed to give pigment flakes having a diameter of 10-80μm. The flakes obtained exhibit an exact cast of the groove structureembossed on the film.

A sample of the powder obtained in this way is dry-coated with thefinger onto a cardboard sheet onto which black and white fields arepressed. On consideration in an inclined view, the pigment powdercoating shimmers in colours which are highly angle-dependent and runthrough virtually the entire spectrum of the rainbow on tilting of thesheet.

Example 2

10 g of the flakes from Example 1 are suspended in 250 ml of water. AnSnCl₄ solution (preparation: 1.1 g of SnCl₄.5H₂O dissolved in 2 ml ofconc. hydrochloric acid and 17 ml of water) is added dropwise at ametering rate of 0.2 ml/min with vigorous stirring at 75° C. and pH 1.8.The temperature is subsequently raised to 90° C., the pH is lowered to1.5, and 20 ml of a TiCl₄ solution (content: 380 g of TiCl₄ per litre)are added dropwise. The pH is kept constant by addition of dilute sodiumhydroxide solution. When the addition is complete, the product obtainedis filtered off, washed and dried, giving a silvery white powder thatexhibits intense angle-dependent interference colours on spreading on asupport.

Example 3

A PET film with a thickness of 0.1 mm whose surface is embossed with aregular groove structure having a frequency of 1000 lines per millimetreand a depth of 150 nm is coated with a 5% aqueous zirconium dioxide sol(particle size 2 nm) using a hand coater. The casting solution wasprepared by dilution of a commercially available zirconium dioxide solfrom Merck KGaA and addition of 0.1% of a commercially available wettingagent (for example Triton® X114). The wet-layer thickness is about 25μm. The aqueous film is dried in air, the dry layer is detached to giveflakes. The zirconium dioxide flakes obtained exhibit a precise copy ofthe surface structure of the film and very intense interference colours.The zirconium dioxide flakes are then calcined at 700° C. and comminutedfurther by means of ultrasound to give pigment flakes. A sample of thepigments obtained in this way is suspended in a nitrocellulose lacquerand applied to a dark-blue plastic card. The coated plastic cardexhibits angle-dependent intense colours over the blue base shade.

Example 4

The film described in Example 3 is coated by the dip-casting method witha 0.5 molar solution of chlorotriisopropyl orthotitanate inhexane/ethanol (1:1 mixture) and dried in air. Firstly a clear gel filmforms, which is slowly converted into titanium oxide in moist air. Atthe end, the film is treated with hot steam, detached from thesubstrate, rubbed down to give flakes and briefly heated to 700° C.After cooling, a white pigment powder is obtained. Spread on a blackboard, the pigment powder exhibits bright angle-dependent colours and astrong glitter effect.

Example 5

Microstructured effect pigments according to Example 1 are admixed witha proportion of 0.1% by weight, based on the total amount, with thepigment powder to be protected (Colorstream® Viola Fantasy, silicondioxide coated with titanium dioxide, tin oxide and zirconium oxide,Merck KGaA). In order to check the protected mixture, the powder isplaced on a specimen slide and investigated by means of a microscope.Under the microscope, the characteristic structuring of the tracer areevident. The addition of the tracer does not result in a change of theapplicational properties of the pigment powder to be protected.

1. Flake-form effect pigments, characterised in that the flakes aretransparent or semitransparent and have a regular groove or gridstructure.
 2. Flake-form effect pigments according to claim 1,characterised in that they consist of one or more layers of transparentor semitransparent materials.
 3. Flake-form effect pigments according toclaim 1, characterised in that the groove or grid structure is locatedon the surface or in the body of the transparent or semitransparentflakes.
 4. Flake-form effect pigments according to claim 1,characterised in that the separations in the groove or grid structureare in the range from 250 to 2000 nm.
 5. Flake-form effect pigmentsaccording to claim 1, characterised in that the transparency of theflakes is >20%.
 6. Flake-form effect pigments according to claim 1,characterised in that the groove or grid structure consists of regularlyarranged lines, hemispheres, spheres, pyramids, cubes or correspondinglyshaped holes.
 7. Flake-form effect pigments according to claim 6,characterised in that the spheres are mono- or multicoated spheres. 8.Flake-form effect pigments according to claim 1, characterised in thatthe transparent or semitransparent materials are magnesium fluoride,metals, metal oxides, metal suboxides, metal nitrides, metal oxynitridesor phosphates.
 9. Flake-form effect pigments according to claim 1,characterised in that at least one of the transparent or semitransparentmaterials has a refractive index >1.7.
 10. Flake-form effect pigmentsaccording to claim 9, characterised in that the material layer having arefractive index >1.7 consists of aluminium oxide, titanium oxide, ironoxide, zirconium oxide or of mixtures of these materials.
 11. Processfor the production of flake-form effect pigments according to claim 1,characterised in that a body provided with a groove or grid structure iscoated with a transparent or semitransparent material, and theflake-form effect pigment is obtained either by detachment from thestructured body or by separation from a support together with thestructured body.
 12. Process according to claim 11, characterised inthat the body provided with a grid structure has regularly arrangedgrooves or spheres.
 13. Process according to claim 12, characterised inthat the spheres are mono- or multicoated spheres.
 14. Process accordingto claim 11, characterised in that the flake-form effect pigments arecoated with further layers of a transparent or semitransparent material.15. Process according to claim 14, characterised in that thesemitransparent material is a metal.
 16. Process according to claim 11,characterised in that the coating is carried out wet-chemically, by thesol-gel process or via PVD or CVD processes.
 17. Use of flake-formeffect pigments according to claim 1 in cosmetics, paints, surfacecoatings, plastics, films, in security printing, as security feature indocuments and identity cards, as tracers, for laser marking, in heatprotection, for colouring seed, for colouring foods or in medicamentcoatings.
 18. Formulations comprising flake-form effect pigmentsaccording to claim 1.